1.Find the values A and B foe following identities in x
a) (A-B)x+(A+B)≡7x+3
b) x2+Ax+10≡(x-2)(x+B) <<<x2=(x)(x)
2.A truck leaves a school at 12:00noon. The truck travels east at 56km/h. At the same time,a van leaves the same school. the van travels north at 42km/h. How far are they apart at 3;00p.m.?
3.Find the number of sides of a regular polygon if each exterior angle is one-third of its corresponding interior angle.
要有step
Maths 問題
2010-08-23 10:27 pm
回答 (2)
2010-08-24 12:50 am
✔ 最佳答案
1a)(a - b)x + (a + b) = 7x + 3
a - b = 7 ... (1)
a + b = 3 ... (2)
(1) - (2), -2b = 4
b = -2
So, a = 9
Ans: a = 9 or b = -2
b)
x^2 + ax + 10 = (x - 2)(x + b)
x^2 + ax + 10 = x^2 + (b - 2)x - 2b
So, -2b = 10, b = -5
a = b - 2 = -5 - 2 = -7
ans: a = -7 b = -5
2)
3hours later, distance between the truck and the school = 56 * 3 = 168km
distance between the van and the school = 42 * 3 = 126 km
So, they are apart sqrt(168^2 + 126^2) = sqrt44100 = sqrt210
3)
let each ext. angle be x and int, angle be y.
3x = y ... (1)
x + y = 360 .. (2)
x + 3x = 360 => 4x = 360 => x = 90
So, each int. angle is 90 degree.
Let there are n sides of that regular polygon.
(n - 2) * 180 = 90n
n - 2 = n/2
2n - 4 = n
n = 4
So, there are 4 sides of the regular polygon
2010-08-24 08:36:55 補充：
sorry
sqrt44100 = 210
參考: My Maths Knowledge
2010-08-24 9:43 am
To LauHenryk:
sqt 44100 is not equal to sqrt 210
Careless mistake. sqrt 44100 = 210
The answer is 210 km. Thanks.
sqt 44100 is not equal to sqrt 210
Careless mistake. sqrt 44100 = 210
The answer is 210 km. Thanks.
收錄日期: 2021-04-29 17:05:49
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